I saw the interface designer Mike Matas was in the list.

Mike Matas joined Facebook a few days ago (incorrect! see bottom), before that he founded Push Pop Press (digital publishing company). For some time he worked at Apple designing new interfaces (presumably iOS7) for iOS and MAC. He was also de founder of Delicious Monster, the makers of Delicious Library, which interface was later copied (inspired?) iBooks from Apple.

Being Mike one of the +400 friends of Zuck and also working at Facebook, I wonder if they where real-friends before being aqui-hired. Or maybe its Zuck adding him as facebook-friends a way of welcoming Mike to the company.

EDIT:PushPopPress was acquired by Facebook 3 years ago, not a few days ago. http://pushpoppress.com/about/